Like nearly all of Martin's SF, this book is set in the Thousand Worlds: a loose far-future history spanning millennia of time and a range of narrative styles. The planet Worlorn is wonderfully named and wonderfully gothic: a rogue planet which happened to drift into the multiple star system called the Hellcrown, beyond the Tempter's Veil. The nearby stellar nations jumped on the opportunity for potlatch, and spent years terraforming and building temporary cities for a decade-long planetary Festival. And now the Festival is over, the tourists are gone, and empty Worlorn is drifting back into the interstellar night.
Tell me that isn't the best SF setting ever.
Dirk t'Larien is haunting some backwater of the Thousand Worlds when he gets a message from Worlorn: a psi-jewel etched with memories of his ex-lover, Gwen Delvano. They once traded promises to come, either to the other, if so summoned. So off he goes. It turns out that Gwen is studying the ecology of the dying planet, and is married... sort of.
The story centers on the society she has married into. The world of High Kavalaan has a history which will be familiar to Bujold fans: loss of spaceflight in a great interregnum, invasion by aliens, nuclear and biological assault, mutation, near-extinction -- and thus a societal swing to xenophobia, obsessive genetic purity, and over-the-top patriarchal wingnuttitude.
Unlike Barrayar, High Kavalaan isn't so much obsessed with honor as with face. Kavalars go armed and ready to duel for called insult. Their women are legally property, which brings us back to the storyline, of course. Jaan, Gwen's lover/husband/owner, is a cosmopolitan guy -- they met on the high-tech world of Avalon -- and their relationship wasn't a problem until he brought her home to meet the family. Specifically, to Jaan's shieldbrother/lover/husband Garse, who is, well, more progressive than Kavalar average but still a shock to Gwen.
The societal clash has pushed the trio out to Worlorn, nominally for ecological research, actually to get away from it all. Inevitably, they brought it with them. Plus there are other Kavalars on Worlorn, for their own not-so-progressive reasons. That's where Dirk walks in -- blind to the whole mess and still carrying a torch for the young Gwen. Tragedy encued.
This is unquestionably a novel about relationships, and unquestionably not a romance; I don't think Martin writes romance, ever. Don't go into this looking for hot OT3. All the relationships are broken, and the characters are trying to feel out new ones. The science-fictionality is that Gwen's position -- emotionally abused, caught between at least four men who all care for her and are hurting her in different ways -- is nonetheless a privileged one; most women on High Kavalaan are rape-fodder locked in basements. I think the point is to knock over the cultural norms and focus on the brokenness. (Readers may disagree about this. But it's safe to say that Martin never implies that Gwen should be grateful for what she's got, and at the end of the book she's created something better.)
Bujold, of course, spends books and years trying to draw what's admirable about Barrayar out from the mountain of blood and pain it rests on. Martin asks the same question about a tougher target. I think he's somewhat clumsy about it -- seriously, rape-fodder in basements, and people hunting humans for sport. We're supposed to believe that most of High Kavalaan has modernized, and is building starships and so on instead of fighting world-wars, but we don't get any sense of social change on this human level -- only Jaan's personal rebellion, and the varying attitudes of the other Kavalars. I think the story would have been stronger for a little more display of Kavalar society and its layers.
(Also, every other planet we might contrast it with is a total cipher. Dirk's viewpoint might as well be 1977-Earth-normal, and the other major society represented in the plot -- Kimdiss, home of another ecologist -- is pacifist cardboard.) (Although, to be fair, Bujold has the same problem in Shards of Honor. We really see nothing of Beta Colony, except as a "sane" foil to "mad" Barrayar, until that brief scene late in the book.)
Nonetheless, and after all that, Dirk does (and we do) get a sense of what High Kavalaan has that is valuable. It may not be much, it may not be what he was hoping for, and it may cost him -- the epilogue makes that clear. But it's better than clinging to a relationship that died seven years ago.